By utilizing the ISM (Industrial-Scientific-Medical) frequency bands, the wireless industry has been able to exploit the increasing popularity of unlicensed communication systems. However, their unlicensed nature carries with it the seeds of serious signal interference problems. Such ISM system designs are type-approved but are then installed by unlicensed owners or
contractors. These conditions sometimes lead to signal configurations that unintentionally interfere. The objective of this article is to present measurement tips and procedures which will help a field technician measure signal interference in operating communications systems.